For example, in printer devices, etc. for use in computers or word processors, various printing systems have been proposed. A thermal transfer recording system is one of these printing systems.
This thermal transfer recording system is uses a thermal transfer ribbon having a thermal fusible ink as an ink layer, and its transfer principle is as follows.
First, a thermal transfer ribbon on which a thermal fusible ink in a solid state at room temperature is coated on a base is caused to be tightly in contact with a transferred paper by pressing force of a thermal head. At this time, the thermal fusible ink which is in a solid state at room temperature is softened and fused by heat of the thermal head. Then, the thermal transfer ribbon is peeled off from the transferred paper when the ink is brought to the solid state for a second time. As a result, the thermal fusible ink at the softened/fused portion is transferred onto the transferred paper. Thus, print, etc. is formed on the transferred paper.
Although, the above-described thermal transfer recording system can simplify the device configuration, and is thus very useful for providing a compact and low cost printer device, it has the following drawbacks.
First, the thermal transfer recording system can only perform binary recording and cannot form graduated images. This is not a significant problem in the case of carrying out only printing, but constitutes a great obstacle in the case of forming a picture (pictorial image).
Further, the recording energy is a large value of 4.about.6 J/cm.sup.2, and the speed is also low. Furthermore, the thermal transfer recording system has a limited pixel density. (In the existing technology, the pixel density of the thermal head has a limit of about 300 dpi).
In addition, there are many problems in view of the running cost and the environmental protection, etc. Namely, an ink of a non-picture portion of the thermal fusible ink is left in the ink ribbon as it is, but the ink remaining in the thermal transfer ribbon cannot be repeatedly used. Accordingly, the greater part of the ink is subjected to disposal. This leads to an increase in the running cost, and results in the possibility that environmental destruction may take place.
On the other hand, as a system for recording a picture, there is also known a system of developing an electrostatic latent image formed on a photosensitive body by a developer in which toners including coloring agent particles are dispersed in a liquid state in an electric insulating dispersion medium. This is called an electrophotographic process. In accordance with the wet developing method, resolution and gradation comparable to silver salt photography can be provided. Especially, a wet developing process using a solidification developer, in which a dispersion medium in a solid state below 30.degree. C. and adapted so that it is fused (molten) by heating and is solidified by cooling is caused to be in a heated and fused state to carry out the wet development is very excellent in view of stability of preservation or handling property, etc. of a developer.
However, in the case of formation of a pictorial image by the above-mentioned wet developing method using solidification developer, there is the problem that transfer of a pictorial image is difficult.
For example, the applicant of this application has already proposed, in the Japanese Patent Application Laid Open No. 81073/1990 publication, a method of heating a developer pictorial image (picture) including a coloring agent (or toner) and a dispersion medium on a base (e.g., a photosensitive body) to allow a transferred body to be in contact therewith in a fused state, thereby transferring the image, or a method of allowing a developer pictorial image (picture) to be in pressure-contact with a transferred body at the time of cooling and solidification to transfer the image.
However, if a transferred body is caused to be in contact with a base (e.g., a photosensitive body) and is peeled off therefrom when a developer pictorial image (picture) is in a fused state, there is the possibility that such a pictorial image may be disturbed uniform transfer is difficult, so unevenness is often observed. Further, in the case where a developer image is caused to be in pressure-contact with a transferred body at the time of cooling and solidification, the developer image cannot be sufficiently transferred, so the quality of a transferred image is remarkably degraded. In addition, there is also the problem that a recorded pictorial image transferred onto a transferred body lacks abrasion resistance.
As described above, in the-thermal transfer recording system, there are the problems that gradation cannot be obtained, and the resolution is insufficient, etc. On the other hand, in the wet developing system using a solidification developer, difficulty of transfer and insufficient durability of a recorded picture, etc. are great problems. Accordingly, solution of these problems is needed.
In view of this, an object of this invention is to provide a picture recording method in which gradation is obtained in a recorded picture, a picture having a high resolution is obtained, and transferability and durability of a recorded picture are both excellent.
In addition, an object of this invention is to provide a picture recording method in which the recording energy for formation of a picture can be reduced, ink is not wastefully consumed, and the recording speed is extremely high.